1. Field of the Invention
The invention relates to a positive crankcase ventilation (PCV) valve installation structure of a blow-by gas recirculation system provided for an internal combustion engine and, more particularly, to a PCV valve installation structure in an internal combustion engine equipped with an oil cooler device that cools lubricating oil.
2. Description of Related Art
In general, a blow-by gas recirculation system for returning blow-by gas to an intake system is provided for an internal combustion engine (hereinafter, simply referred to as engine) mounted on an automobile, or the like. In addition, there is a V-engine in which cylinder banks are arranged in a V shape centering on a crankshaft as one type of the engine of an automobile. Then, a blow-by gas recirculation system is also provided for the V-engine as well.
In a related art, there is known a blow-by gas recirculation system that is provided for such a V-engine and in which, as shown in FIG. 7, PCV valves 100 and 101 are attached to corresponding cylinder head covers 102 and 103 (for example, see Japanese Patent Application Publication No. 2007-224736 (JP-2007-224736)). For example, in a left bank 105 of such a V-engine 104, an existing blow-by gas recirculation system 106 includes a separator case 107 that is provided for the cylinder head cover 102 and that separates blow-by gas and oil mist from each other, the left PCV valve 100 that emits the blow-by gas separated by the separator case 107 and a left blow-by gas supply tube 108 that couples the left PCV valve 100 to an intake pipe at a portion downstream of a throttle valve. In addition, in a right bank 109 of the V-engine 104, an existing blow-by gas recirculation system 110 includes a separator case 111 that is provided for the cylinder head cover 103, the right PCV valve 101 that emits blow-by gas separated by the separator case 111 and a right blow-by gas supply tube 112 that couples the right PCV valve 101 to the intake pipe at a portion downstream of the throttle valve. These two PCV valves 100 and 101 are exposed to an engine room.
With such a configuration, in the blow-by gas recirculation systems 106 and 110, for example, when the left PCV valve 100 of the left bank 105 is open and the right PCV valve 101 of the right bank 109 is closed, blow-by gas blown through a gap between a cylinder 113 and a piston 114 into a crank chamber 115 in a compression cycle or expansion cycle of the V-engine 104 is introduced into the separator case 107 via a blow-by gas passage 116 and cam chamber 117 of the left bank 105. Blow-by gas from which oil mist is separated and removed by the separator case 107 flows out to the left blow-by gas supply tube 108 via the left PCV valve 100, and is introduced into the intake pipe at a portion downstream of the throttle valve.
On the other hand, there is suggested a blow-by gas recirculation system that is provided for a V-engine and that has a breather between left and right banks (for example, see Japanese Patent Application Publication No. 2006-70833 (JP-A-2006-70833)). In this blow-by gas recirculation system, blow-by gas that has reached a breather chamber from a crank chamber is separated into gas and liquid in the breather chamber. Then, blow-by gas from which oil mist is separated is emitted through a blow-by gas introducing hole formed above the breather chamber.
However, in the existing blow-by gas recirculation systems 106 and 110 in which the PCV valves 100 and 101 are respectively provided for the cylinder head covers 102 and 103 as described above, the PCV valves 100 and 101 are exposed to the engine room, and the PCV valves 100 and 101 do not have a heating mechanism, such as a heater, so there is a problem that the PCV valves 100 and 101 may freeze because of running wind while the automobile equipped with the blow-by gas recirculation systems 106 and 110 is running in an environment below freezing. When the PCV valves 100 and 101 freeze, blow-by gas is not emitted from the crank chamber 115, so degradation of lubricating oil may be facilitated.
In addition, in the existing blow-by gas recirculation system having the breather chamber between the left and right banks as described above, the PCV valve is assumed to be installed at a blow-by gas introducing hole above the breather chamber, so, as in the case where the PCV valves 100 and 101 are respectively provided for the cylinder head covers 102 and 103 as described above, the PCV valve may freeze because of running wind while an automobile equipped with the blow-by gas recirculation system is running in an environment below freezing.
On the other hand, in order to prevent freeze of the PCV valve, it is conceivable to provide a heating mechanism, such as a heater, around the PCV valve; however, in this case, the number of components increases to lead to a complex configuration and increased component cost.